Rear disc shields replacement

[ReadingMBR]

Need to get the car (R350 CDI) in for new rear discs and pads and noticed that the shield is quite rusty, hardly surprising after 92k and 9 years. Is it an expensive job / recommended ?

 

[LostKiwi]

It requires the hub to be removed so is a lot of labour.

 

[umblecumbuz]

Not sure on your model, but I have replaced rear tin brake shields on earlier C-class cars by cutting a slot in the tin and 'easing' the shield over the hub assembly, then bending the shield back into alignment and securing normally. A lick of paint on the cut edges finished the job.

Maybe someone on here has done something similar with a W251.

 

[EmilysDad]

Wire brush & a tin of Hammerite smooth ..... far too much effort replacing something you can't see

 

[ReadingMBR]

Cheers all

 

[ZZZZ]

Been there - when I bought this car, three years ago, Mercedes said [strictly following the script] " brake dicsc and pads need replacing", so I bought a set of new discs and pads, and, as the brake back plates were horribly rusty, I also bought a set of brand new ones, from MB Newcastle eBay store (feeling pretty smug about it too).

When I brought the whole braking menagerie to Nick, at Parkham Garage, he said "don't be stupid", then wire-brush cleaned and Hammerite painted the back plates, and fitted my new drilled and grooved brake discs and OE pads.

MB Newcastle was kind enough, to accept the brake plates back, and refund in full.

Three years later, the back plates look pretty good ... can't say the same of the MTEC discs - look good when new, but rust at the first fart ... err ... I mean first sign of moisture in the air.

 

[magsbert]

Not sure on your model, but I have replaced rear tin brake shields on earlier C-class cars by cutting a slot in the tin and 'easing' the shield over the hub assembly, then bending the shield back into alignment and securing normally. A lick of paint on the cut edges finished the job.

Maybe someone on here has done something similar with a W251.

Yes have done this job C-class coup,parts guy at Mercedes sells plenty of backing plates but very few rear hub bearing,this suggests cutting back plate is the most common repair method regards.

 

[Droverunner]

Mrs D's CLK has just educated me in the ways of the rear disc shield so thought I'd share some pics of the job over a few posts as I get it sorted.

Last week I fitted new rear discs/pads to cure judder. The nearside went OK but as soon as I went to gently pull off the offside rear disc/drum it locked up about 1/2" pulled away and I could see the handbrake shoes had become displaced so assumed the holding spring/s had broken. When I finally removed the disc I found both the slots for the shoe retaining springs had enlarged due to being paper thin with rust.

Reading up on the forums and watching YouTube made me decide to use the cut shield method of replacement rather than remove the hub.

Once you've removed the disc and caliper the extra work to remove the hub to fit the shield by the book involves removing/replacing six suspension links, the handbrake cable and anti-lock sensor then getting a garage with a press to remove the hub/bearing and fit the shield and new bearing. A crazy amount of work compared with a couple of inches hacksawing.

Crucial to making a good job is how much you cut and where. I've seen procedures where far more is cut than needed and in one case on YouTube the guy just cuts off about 30% of the disc shield throwing it away so exposing the handbrake mechanism and shoes to road dirt.

I bought a gen MB shield as on a fiddly job I didn't want to find any aspect of a pattern shield a few mm out adding extra hassle.

 

[Droverunner]

I thought the four shield retaining bolts might be rusted in but they came out OK... two needed female E10 torx sockets and two a 13mm ring spanner as I couldn't quite get a socket to line up. Getting the old shield off was easy given its thin rusted state... two tin snips cuts roughly where I intended to cut the new one were sufficient... plus pushing the pin from the handbrake expander/cable link so that could be taken out the way.

 

[Droverunner]

Regarding the hacksaw cuts on the new shield its obvious the main one would be the narrow part where its cut away for the caliper but I didn't make a cut next to the bolt as some folks but right through the middle of the bolt hole so with the addition of a slightly oversize washer the bolt would pull both parts into place on the hub casting (the pic makes it look as if I'm about to cut to one side but that's the camera angle).

The second opposite cut seemed most logical through the aperture for the handbrake mechanism and I cut a few mm at a time constantly trying to get it over the hub flange so I cut the minimum away to get it on without bending the shield out of shape too much.

I used a hobby hacksaw to keep the cuts as thin as possible. They look a bit wider than they are as I was yet to pull it back into shape which only happened once the bolts were in and tightened.

 

[Droverunner]

I closed the hacksaw slots with a waterproof building trade black sealer/adhesive made for gutters etc. Once bolted up the disc shield has regained 99.9% of its stiffness so I'm totally happy with the method. I think I'll do the nearside shield as a routine job soon as it will probably be not too far behind in condition and I'd rather the shoe retaining springs didn't fall out on a long run.

 

[joderest]

That is such a neat job, (hand clap). It is something i will bear in mind.

 

[Blobcat]

Looks good, I'd be tempted to get the Mig in there if at all possible and stick it together

 

[Droverunner]

You could if you wanted to but no need (I don't weld anyway). The shield will be 100% functional re dust/dirt just with those minimal cuts and sealer... plus the way the 4 bolts pull it tight to the hub casting the handbrake shoe "pads" are located mm perfect.

 

[M80]

Looks good, I'd be tempted to get the Mig in there if at all possible and stick it together

I would be scared of going anywhere near the delicate electronics of a car with a MIG.

 

[Droverunner]

Just an update from once the job was completed. If doing again I'd fit the disc back on and bolt up to ensure it span without rubbing any part of the shield before fitting the handbrake shoes. In my case there was a rubbing and I assumed it was the handbrake shoes so wasted 20 mins faffing trying to adjust the rub away. Turned out to be the new shield where the rear lip of the disc runs close to a groove in the shield. Once I'd realised just two taps of the hammer fettled it the required couple of mm to clear.

 

[Lexy]

This is excellent - will have a go following this method this weekend. Thanks a lot.

 

[Madtutle3]

I had this method used on my '92 Subaru SVX. Worked great and way cheaper than pulling the hubs.

 

[Lexy]

This works a treat. Followed exactly as described and no issues at all. Thanks very much for sharing.